Mapping Collaboration in Astronomy

A couple of weeks ago I began to geocode the database of astronomical research I scraped from NASA ADS during .Astronomy 4. This database consists of all the published astronomical research in five major journals (almost 250,000 papers going back decades, from MNRAS, ApJ, AJ, A&A and PASP) up to July 2012. You can read more about that here and here.

Geocoding is the process by which latitude and longitude are derived from a sting of text, e.g. a street address. You use it all the time if you use Google Maps, Bing Maps, or whatever Yahoo call their maps (Yahoo Maps?). The recent débâcle over the failure of the iPhone’s mapping service mostly comes down to the fact that Apple’s geocoding capabilities are not up to scratch.

I’ve been using a Ruby Gem called Geocoder to obtain a latitude and longitude for the affiliations of authors in the astro-literature. Why? Well I thought it be interesting to see how astronomers around the world collaborate. The idea is that we can take those lists of co-authors and visualise how each university or research centre works with the others.

To do this I take a map of the world and every time two institutions work together on a paper I draw a link between them. I do this in R, which fun to try out, and there is a great guide at this site here. Each single line is drawn very faintly but you can see that they quickly build up. The result are maps like this one below:

This map shows only the connections between European nations and only in 2005. Those research centres that work most with others pop out fairly easily: Paris, Edinburgh, ESO/Max-Planck in Garching, Germany. Paris (Saclay) in particular is very strongly linked with many places in Europe. My home institution of Oxford can just be picked out in the very busy UK. You can easily make out many of the areas which were less involved in the astronomy-research community in 2005: Northwestern France, Norway and much of Eastern Europe.

On this map, big collaborations dominate. If there is a paper with ten different institutions represented then all ten of those institutions will be highlighted. One big collaboration would make a fairly complex web on its own. In 2009 the was a paper published by the LIGO consortium, involving more than 700 authors from a huge range of research centres around the world. This makes the 2009 plot for Europe, and virtually anywhere else, look quite busy.

The journals I’ve picked are large but they are only English-language. That’s because of my own bias, since I wouldn’t be able to check my working if I dealt with all the major journals from all languages. Also, I have no idea what journals exist for astronomers outside of the English-speaking world and I’m aware that English is fairly dominant in astronomy worldwide. You have to take this into account when looking at the maps.

In all these plots the intensity of the colour is normalised, such that the peak strength of connection is always set to be 100% opaque and it works down from there (linearly, if you’re still following). This means that where you see relatively bright arcs all over the map, it shows you that each place is collaborating with each other fairly evenly. When you see just a few bright arcs, it shows that those places work together a lot more relative to the others.

Here’s Europe changing slightly, over the last few years:

Lets look now at North America. Here is the plot for 2009:

You can see a clear band of strong connections between California and the North-East of the country (roughly). There are also myriad other links drawm more faintly. Honolulu and Mauna Kea are clearly highlighted, jumping out from the Pacific – and of course this is no surprise since many major telescopes are to be found there.

Now let’s see how Europe and the USA link up. These are the two hubs of English-speaking astronomy. Here’s a plot showing links between all these places in 2008.

The strength across the atlantic is very intense – just as strong as within: showing that an ocean’s gap between them has little effect in working terms for the USA and Europe. With astronomy this doesn’t surprise me. Many of the big telescopes are in the US for starters. But also, researchers go where the money is and will happily jump across the pond when needed. The global picture also reveals great collaborative efforts within astrophysics increase as the years go by.

I’ve made a set of these global and regional maps that can be found on Flickr.

The other approach is to highlight all the links to and from just one institution. Let’s take Oxford University, since it’s where I currently work:

This is the map for 2010 and you can see that Oxford, as a major astronomy reseach centre, has links to a lot of places. More interestingly, you can also see how these connections weigh against each other. Oxford is no more tied to Europe than America and appears to collaborate across the UK fairly extensively.

If we use the same intensity scale and compare this to my former institution, Cardiff, in the same year:

then we can see that the pattern is slightly different. Cardiff is less linked in general but has stronger connections to several locations, many European. This must be in large part due to the fact that several important instruments were built here, for Herschel and Planck. The instruments on these spacecraft, and the consortia that operate them, have been the source of a great deal of collaboration in the last few years. 2010 was a notable year for publications from those instruments.

Finally there are regions I know little about, but which appear to tell their own stories when I look at the maps. Take Australia, for example:

This map of 2010 activity down under shows Sydney as the leading collaborator in the region. It also shows that New Zealand and Australia coperarte broadly in astronomy research. In East Asia in 2010 the map shows again that there are a variety of insititutions cooperating on papers, but that Tokyo appears to be a key hub in the community.